Exemplary embodiments relate to a semiconductor device, and in particular, to methods of forming a stack of electrodes and three-dimensional semiconductor devices fabricated thereby.
Higher integration of semiconductor devices is required to satisfy consumer demands for superior performance and lower prices. In the case of semiconductor memory devices, integration is an important factor in determining product prices and thus, increased integration is important. In the case of typical two-dimensional or planar semiconductor memory devices, their integration is mainly determined by the area occupied by a unit memory cell, and thus, integration is greatly influenced by the level of a fine pattern forming technology. However, the extremely expensive process equipment needed to increase pattern fineness sets a practical limitation on increasing integration for two-dimensional or planar semiconductor devices.
To overcome such a limitation, three-dimensional semiconductor memory devices having three-dimensionally arranged memory cells have been proposed. The three-dimensional semiconductor memory device may also include three-dimensionally arranged conductive lines (for example, word lines) serving as electrical paths for accessing the memory cells.